Quartz. I'm tracing four wavelengths as proposed by the Hero paper, but I have not implemented their MIS scheme yet. In this case it's useless by the way; the quartz will reduce weights for all wavelengths but the hero to zero anyway. For the floor and walls the four wavelengths are very effective, obviously.

It describes a fast and accurate way to generate an orthonormal basis for things like random sampling. I got the link from a Twitter post by Carmack some time ago but I don't remember seeing it linked here yet.

I watched the Hero presentation at EGSR a couple years back. The results looked really excellent.

Whoah, weird. I had thought you could do something very similar, but by adding a random point on the *interior* of a sphere to the normal, rather than on the surface: http://psgraphics.blogspot.com/2014/09/ ... -rays.html. Obviously it would be better to use exactly two random parameters than an unbounded number of them, but I have a hard time wrapping my brain around the possibility that both are correct.